The dramatic increase of popularity of the Internet has led to a corresponding dramatic rise in the popularity of textual communications such as e-mail and instant messaging. Increasingly, browsing of the World Wide Web of the Internet and textual communications are being performing using reduced keypads such as those found on mobile telephones.
Use of such reduced keypads for entering text in the Roman alphabet is manageable since there are only 26 letters in the Roman alphabet. Accordingly, generally three (3) or four (4) letters are mapped to each of eight (8) numerical keys as can be seen printed on numeric keypads on the vast majority of telephones sold in the United States. By having so few letters associated with each key, multi-tap systems provide useable but less than convenient text entry functionality for users of the Roman alphabet. Briefly, multi-tap systems determine a number of repeated presses of a key to disambiguate multiple letters associated with a single key. For example, pressing the “2” key once represents the letter “a”; pressing the “2” key twice represents the letter “b”; pressing the “2” key thrice represents the letter “c”; and pressing the “2” key four (4) times represents the numeral “2”. The number of presses of a particular key is typically delimited with a brief pause.
While feasible, entering textual data of the Roman alphabet using multi-tap is cumbersome and time-consuming. However, text entry for other written languages which include many more symbols is even more difficult. In particular, Chinese is written using as many as 10,000 distinct characters, Japanese is written using 7,100 or more distinct characters, and Korean is written using roughly 11,000 distinct characters. Mapping so many distinct characters to ten (10) numeric keys of a telephone keypad would require approximately 70 to 110 distinct characters per key. Accordingly, multi-tap is not feasible to disambiguate among so many distinct characters mapped to a single keypad key.
Japanese and Korean written languages mitigate this problem to some degree as written Japanese can be accomplished using approximately seventy-five (75) distinct symbols associated with the Japanese “fifty-sounds table” and written Korean symbols (called hanguls) are composed using approximately forty (40) sub-symbols (called jamos). Even so, mapping 40–50 distinct written symbols to the ten (10) numeric keys of a standard telephone keypad makes multi-tap approximately twice as complex and inconvenient as multi-tap is for the Roman alphabet.
Some attempts have been made to use predictive interpretation of key presses to disambiguate multiple written symbols associated with various keys. Such predictive interpretation is described by Zi Corporation at http://www.zicorp.com on the World Wide Web and in U.S. Pat. No. 5,109,352 to Robert B. O'Dell (hereinafter the O'Dell Patent). Predictive interpretation is generally effective and greatly simplifies text input using reduced keypads and very large collections of written symbols. However, predictive interpretation has difficulty with words used in proper nouns, slang, and neology as such words might not be represented in a predictive database.
What is needed is an improved mechanism for disambiguating among multiple symbols associated with individual keys of a reduced keypad.